Impact of Earthworm Introduction on Litter Burial and Nutrient Distribution in Ohio Strip‐Mine Spoil Banks

Abstract

AbstractEarthworms (Lumbricus terrestris L.) actively buried leaf litter and humus, and deposited castings on the surface of an acid (pH 3.5–4.0) shale spoil bank revegetated with black locust (Robinia pseudoacacia L.). Earthworms persisted for 5 years in the coal spoils and buried or consumed the equivalent of 5 metric tons of leaf litter/ha. In a greenhouse study, earth‐worms in cores of spoil from the mined area buried or consumed a 60‐mm thick layer of litter and humus in 174 days. The equivalent of 9.5 metric tons of litter and 52.5 metric tons of humus was buried or consumed/ha, while the equivalent of 16.7 metric tons of castings was deposited on the surface. Exchangeable cations and available P in the mineral spoils increased as follows: K from 0.17 to 0.19, Ca from 1.7 to 2.7, and Mg from 1.8 to 2.5 meq/100 g of spoil; and available P increased from 1.7 to 4.2 ppm. Earthworm activity did not influence growth of northern red oak (Quercus rubra L.) seedlings planted in the cores.In another study, 10 Lumbricus terrestris were introduced on a calcareous strip‐mine spoil revegetated with European alder (Alnus glutinosa L.). In 5 years, the earthworm population increased to a density of 60 middens/m2 over an area of 700 m2.Clearly, earthworms can be established on revegetated coal spoil banks, where they promote incorporation of organic matter into the mineral spoil.